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<b>let </b><font color="Maroon">a</font> be  <a href="xxreal_0.html#V1" target="_self">ext-real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/><b>let </b><font color="Maroon">b</font> be  <a href="xxreal_0.html#V1" target="_self">ext-real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>



<b>assume </b><b>that </b><br/><a NAME="E1:22"/><i><font color="Green">E19</font></i>: 
<font color="Maroon">a</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K1">REAL</a> 
 <b>and </b><br/><a NAME="E2:22"/><i><font color="Green">E20</font></i>: 
<font color="Maroon">b</font> <a href="xxreal_0.html#R1" target="_self">&lt;=</a> <font color="Maroon">a</font>
 ;<br/>

<b>assume </b><a NAME="E3:22"/><i><font color="Green">E21</font></i>: 
not <font color="Maroon">b</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K1">REAL</a> 
 ;<br/>

<a NAME="E4:22"/>
( <font color="Maroon">b</font> <a href="hidden.html#R1">=</a>  <a href="xxreal_0.html#K1" target="_self">+infty</a>  implies <font color="Maroon">a</font> <a href="hidden.html#R1">=</a>  <a href="xxreal_0.html#K1" target="_self">+infty</a>  )
 
<b>by </b><i><a class="txt" href="xxreal_0.html#E2:22"><i><font color="Green">E20</font></i></a>, </i>;<br/>
<b>hence </b><a NAME="E5:22"/>
<font color="Maroon">b</font> <a href="hidden.html#R1">=</a>  <a href="xxreal_0.html#K2" target="_self">-infty</a> 
 <b>by </b><i><a class="txt" href="xxreal_0.html#E3:22"><i><font color="Green">E21</font></i></a>, , <a class="txt" href="xxreal_0.html#E1:22"><i><font color="Green">E19</font></i></a></i>;<br/>


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